1. Field of the Invention
The present invention generally relates to an electrical interconnection, and more particularly to an interconnection within an electrical system in which a plurality of stationary boards and a plurality of removable boards are installed and arranged in a matrix form.
2. Description of Related Art
Various electronic systems, especially a telecommunication system, router, server and switch, comprise a wide array of components mounted on printed circuit boards, such as daughter boards and motherboards. The mother board to which the daughter boards are connected is generally referred to as backplane as it is stationary. Connectors used to assemble the daughterboards, which are removable, to the motherboards are referred to as backplane connectors. The mother board and the daughter board are interconnected by the connectors so as to transfer signals or power throughout the systems.
Typically, the motherboard, or backplane, is a printed circuit board that is mounted in a server or a switch and is provided with a plurality of backplane connectors. Multiple daughterboards are also each provided with a mating connector and then removably plugged into the connectors on the backplane. All the daughterboards are interconnected to the backplane, the daughterboards are interconnected through the backplane and are arranged parallel to each other.
However, connecting the daughterboards via the backplane leads to the potential for signal interference. Because the daughterboards are all connected via the backplane, signal strength may be attenuated as signals travel through the backplane. In general, signals passing between two daughterboards pass through at least a first connector pair between a first daughter board and the backplane, and a second connector pair between the backplane and a second daughter board. In general, the signal passes through a total of two pairs of mated connectors, and each time the signal is attenuated as it passes.
Generally, the arrangement between the backplane and the daughter board can be referred to as a “TTTT” type viewed from a top, i.e. the backplane is arranged in a horizontal direction, while the daughter board is arranged in a position perpendicular to the backplane. In some cases, both sides of the backplane are provided with connectors for assembling the daughterboards from both sides. This arrangement can be referred to as a “++++” type viewed from a top. In this arrangement, the daughterboards arranged in both sides are in communication with each other through the motherboard, i.e., mid-plane.
Many connectors have been provided for achieving such arrangement. U.S. Pat. No. 5,993,259 (the '259 patent) issued to Stokoe et al. discloses an electrical connector of such application. The connector disclosed in the '259 patent includes a plurality of modularized wafers bounded together. As shown in FIG. 4 of the '259 patent, the terminals are stamped from a metal sheet and then embedded within insulative material to form the wafer.
U.S. Pat. No. 6,083,047 issued to Paagman discloses an approach to make a high-density connector by introducing the use of printed circuit boards. Conductive traces are formed on surfaces of the printed circuit board in a mirror-image arrangement.
U.S. Pat. No. 7,108,556 issued to Cohen et al. discloses a similar configuration.
U.S. Pat. No. 5,356,301 issued to Champion et al. discloses a pair of back-to-back arranged plug connectors mounted on opposite sides of a motherboard via common contacts for respectively connecting with a receptacle connector mounted on a daughter board and a cable connector.
However, all connectors suggested above are all mounted on the backplane or mid-plane. As can be understood, if the mid-plane can be eliminated such that the daughterboards can be interconnected with each other through as few connectors as possible, then the signal attenuation as well as the interference can be largely reduced. However, none of the connectors provided yet meets such a requirement.
U.S. Pat. No. 6,918,775 (the '775 patent) issued on Jul. 19, 2005 discloses eliminating the mid-plane. A connector disclosed in the '775 patent could interconnect a stationary board and a removable board, under a cooperation between an actuator and a plurality of contacts. A plurality of first ends and second ends of the contacts electrically abut against a plurality of conductive pads of the stationary board and the removable board, respectively, for delivering signals.
However, when the connector is electrically connected to different types of signals, the signals could not be transmitted in sequence.
Hence, an improved electrical interconnection system is required to overcome the above-mentioned disadvantages of the related art.